Earlier quoted context omitted.
The relevant code was (allegedly) not part of source control, but inserted during the build process.
Hmm, interesting. I'm confused if that's how I should read this. You might be right. I assume you're referring to this paragraph? > Evidence suggests that as early as October 2019, these attackers have been testing their ability to insert code by adding empty classes. Therefore, insertion of malicious code into the SolarWinds.Orion.Core.BusinessLayer.dll likely occurred at an early stage, before the final stages of t…
https://www.solarwinds.com/securityadvisory/faq
> Our initial investigations point to an issue in the Orion software build system in which the vulnerability was insert which, if present and activated, could potentially allow an attacker to compromise the server on which the Orion Platform products run.
Under "With these processes in place how was your code compromised?"